Pneumatic tube systems are widely used in commercial applications to move articles from one location to another location. Pneumatic tube systems generally utilize a hollow cylinder or “carrier” in which the materials are placed for transport within the system. The carrier containing the materials to be transported travels through pneumatic travel tubes. Such systems have been used in department stores and banks for bi-directionally movement of currency, deposit slips, sales slips, and the like between the ends of a single tube.
Pneumatic tube systems are also commonly used in hospitals and similar medical facilities for the rapid movement of medicines, supplies, and biological samples within the building. In this setting, the user needs a more complex system than a single tube because the system must move carriers to different stations on different floors. In one application, the pharmacy may need to send carriers containing medication to one of many possible nurse's stations. The nurse's station may need to send carriers containing blood samples to the lab for analysis. In another situation, the pharmacy may want to send the medication directly to the emergency room. In such complex arrangements, a system of dedicated tubes having single end points would be impractical since multiple tubes would need to run to each of many locations.
To overcome this problem, “diverters”, such as those described in U.S. Pat. No. 4,529,335 have been used. Briefly, a diverter has a plurality of tubes terminating in a revolving cylinder. FIG. 1 illustrates source station 10 sending a carrier through diverter 12. The diverter receives a carrier from tube 14, rotates, and then sends the carrier back out another tube, e.g., tubes 16, 18, 20, and 22. For example, a carrier from station 10 (pharmacy) travels into a diverter and stops. The diverter rotates until it is aligned with a desired exit tube. The blower then turns on and sends the carrier back out through the selected exit tube to the desired end location (nurse's station), possibly on a different floor of the hospital.
The number of locations in either direction that can be serviced is increased by employing multiple diverters. FIG. 1 illustrates diverters 30, 32, 34, and 36 being connected to tubes 16-22, respectively. Diverter 30 also connects to tubes 38, 40, 42, and 44; diverter 32 also connects to tubes 46, 48, 50, and 52; diverter 34 also connects to tubes 54, 56, 58, and 60; diverter 36 also connects to tubes 62, 64, 66, and 68. Stations 70, 72, 74, and 76 connect to tubes 38, 40, 42, and 44, respectively. Stations 78, 80, 82, and 84 connect to tubes 46, 48, 50, and 52, respectively. Stations 86, 88, 90, and 92 connect to tubes 54, 56, 58, and 60, respectively. Stations 94, 96, 97, and 98 connect to tubes 62, 64, 66, and 68, respectively.
Station 10 can route a carrier to station 70 by way of diverter 12 and diverter 30. The carrier is routed from station 10 to diverter 12 by way of tube 14 and stops. Diverter 12 rotates to align with tube 16. The carrier is then routed to diverter 30 and stops. Diverter 30 rotates to align with tube 38. The carrier is routed to station 70. In another example, station 72 can send a carrier to station 98 by way of diverter 30, diverter 12, and diverter 36. The carrier is routed from station 72 to diverter 30 by way of tube 40 and stops. Diverter 30 rotates to align with tube 16. The carrier is then routed to diverter 12 and stops. Diverter 12 rotates to align with tube 22. The carrier is then routed to diverter 36 and stops. Diverter 36 rotates to align with tube 68. The carrier is routed to station 98. A return trip from station 98 to station 72, which is common, uses the same tubes and diverters in the opposite order. The carrier moving from station 72 to station 98 and back again may require eight diverter rotations plus two carrier stops plus two carrier starts each by three different diverters. In general, the carrier may be required to stop at each diverter depending on the specific layout.
Yet, even with the flexibility of the pneumatic system of FIG. 1, the number of inlet and outlet tubes possible on any given diverter is limited due to space concerns and limitations on the size of the rotational mechanisms. In addition, each station is an end point that relies upon a dedicated diverter for sending and receiving a carrier. Accordingly, the needs of even a modest hospital require many diverters in order to service the large number of entry points. Diverters also increase travel time due to stoppage of the carrier and the rotation to align with different tubes, increase maintenance costs due to failure of the moving parts of the diverters, and have relatively high capital costs.
Accordingly, a need exists for a pneumatic transport system that decreases travel time and reduces system capital costs.